Process of manufacturing spaced plate arc extinguishers



Feb. 14, 1956 R. E. FRINK ETAL 2,734,842

PROCESS OF MANUFACTURING SPACED PLATE ARC EXTINGUISHERS Original Filed Feb. 25, 1949 2 Sheets-Sheet l Cemenhhoua 28 Material Fig. 3.

Fig.4.

WITNESSES:

04 flew a INVENTORS Russell E. Frink and Robert C. Dickinson Feb. 1956 R. E. FRINK ETAL PROCESS OF MANUFACTURING SPACED PLATE ARC EXTINGUISHERS 2 Sheets-Sheet 2 Original Filed Feb. 23, 1949 INVENTORS Russell E. Frink and Robert C. Dickinson ATTORNEY United States Patent PROCESS OF MANUFACTURING SPACED PLATE ARC EXTINGUISHERS Russell E. Frink and Robert C. Dickinson, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Original application February 23, 1949, Serial No. 77,793, now Patent No. 2,610,937, dated September 16, 1952. Divided and this application February 16, 1952, Serial No. 271,924

2 Claims. (Cl. 154-122) This invention relates generally to circuit interrupters, and more particularly to an improved process of manufacturing spaced plate type of air break circuit interrupters.

This application is a division of applicants parent application filed February 23, 1949, Serial No. 77,793, issued September 16, 1952, as United States Patent 2,610,937, entitled Process of Manufacturing Spaced Plate Arc Extinguishers, and assigned to the assignee of the instant application.

The invention relates to air-type spaced plate circuit interrupters, particularly of the slotted plate type, in which the established arc'is moved laterally into the aligned slots provided by the several plates, to the closed ends of said slots where the arc is extinguished. Either a magnetic field may be provided to force the are into the aligned slots to eflect the extinction thereof at the closed ends of the slots, or a gas blast or other are moving means may be employed. Reference may be had to U. S. Patent No. 2,442,199, which issued May 25, 1948, to Robert C. Dickinson and Russell E. Frink, and which is assigned to the assignee of the present application. This patent discloses the particular constructional details of the air break slotted plate type of circuit interrupter under consideration and also describes the theory of arc interruption.

The spaced plate type of circuit interrupter referred to in the aforesaid patent is made from a number of flat rectangular ceramic plates having V-shaped notches or slots extending inwardly from one end of the plates. The slots are unsymmetrical about the center line of the plates and are alternately staggered in the assembling operation as set forth in the aforesaid patent. These plates are stacked with spacers between the edges, leaving vent spaces between adjacent plates. The plates are placed with the open ends of the slots lined up, but with the offset staggered from side to side so that when the arc is driven up into the slots it is restricted and lengthened, and eventually interrupted in the manner described in the aforesaid patent.

The stack assembly is cemented together and baked to make it, for all practical purposes, a single unit. The individual plates are a high fired ceramic, and for that reason are not perfectly straight and true. They are also rather fragile. The spacers, which are placed between these plates must have enough fiexibilityto allow for this unevenness and still form a gas-tight joint. They must also be able to stand high temperature from the arc and preferably must be free from carbonization.

Our invention eliminates the use of separate spacer strips which have been made from a high grade asbestos rope packing and placed at the edge of the plates. We eliminate the preparatory step of running the rope through rollers to make it oblong in cross-section and bring it down to size. We also make it unnecessary for the workman to paint the edges of the plates with cement, and to manually place the rope spacers in place on the cement.

It is a general object of our invention to improve the flr' 2,734,842 Ce Patented Feb. 1

method of manufacture of the stack of plates so that considerable time will be saved and hence the cost of production greatly reduced.

It is a further object of our invention to provide an improved method of manufacture of the interrupting plate assembly by the automatic disposition of a heavy-bodied cement between the plates so as to eliminate the use of separate spacer strips and speed up the manufacturing processes and give a uniform product.

Further objects and advantages will readily become apparent upon reading the following specification taken in conjunction with the drawings, in which:

Figure l is a side elevational view, partly in vertical section, of an air break spaced plate type of circuit interrupter indicating the type of apparatus under consideration and in which an assembled stack of slotted spaced plates is utilized;

Fig. 2 is an enlarged plan view of one of the individual plates utilized in the circuit interrupter of Fig. 1, showing also the two lengths of spacing material at the edges of the plate;

Fig. 3 is a side elevational view, partly in vertical section, and partly diagrammatic, indicating one possible form of apparatus used in our improved process and shown at an intermediate step in the assembling operation;

Fig. 4 is an end elevational view of the apparatus shown in Fig. 3;

Fig. 5 is a perspective view illustrating one step of a process of manufacture which is variant to that shown in Figs. 3 and 4;

Fig. 6 is a perspective view of a plate assembly showing the stepped spacer arrangement, and also showing the manner of forcing cement between the side edges of the ceramic plates in the arc extinguishing stack;

Fig. 7 is a perspective view similar to that of Fig. 6, but indicating how the ribbons of cement are reduced in thickness by partial removal of the stepped spacers preliminary to the baking operation; and

Fig. 8 illustrates another method of applying the cement in a sheet to one side of the stack.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral 1 generally designates contact structure which when separated, as shown, draws an are 2, which, because of the loop circuit provided, moves upwardly into engagement with the arc horns 3, 4. The position of the are at this time of operation is designated by the reference numeral 5. Suitable plate structure generally designated by the reference character 6 is provided, which is composed of a plurality of spaced plates 7 (Fig. 2), each of which has an unsymmetrical elongated slot 8 provided therein.

' The several plates 7 are preferably of a high-fired insulating ceramic and are spaced apart by spacer strips 9 so that an exhaust passage 10 extends upwardly out of the arc chute between adjacent plates 7. The are is forced by the energization of the blow-out coil 11 up into the slots 8 in a manner described in the aforesaid patent, and are extinction occurs at the upper closed ends of the slots 8, with the exhaust gases passing upwardly between the plates 7 and out of the interrupter through the exhaust passages 10.

Figs. 3 and 4 show one possible form of apparatus which may be utilized in our improved process to speed up the assembling operation, and at the same time insuring uniform width of the spacing strips 9 at the edges of the plates 8. Referring to Figs. 3 and 4, it will be observed that we have provided a gun 12 having two nozzles 13, 14 which extrude cement in ribbon form along the outside edges of the several plates 7. Insulating spacer strips 15 are employed to maintain the spacing to the desired width prior to the baking operations. It will be noted that the plates 7 are moved by a carriage structure 16 mounted on rollers 17, the latter riding on a platform 18 diagrammatically represented. At the opposite ends of travel of the carriage 16 are limit switches 19, 20, each of which serves to deenergize a solenoid 21 encircling an armature 22. The deenergization of the solenoid 21 closes a valve structure generally designated by the reference numeral 23 associated with each nozzle 13, 14.

More specifically, the valve structure 23 includes an apertured valve plate 24, biased toward the left, as shown in Fig. 3, by a tension spring 25. Consequently, energization of the solenoid 21 during the intermediate portion of travel of the carriage 16 serves to attract the armature 22 toward the right, as viewed in Fig. 3, to bring the aperture 26 of the plate 24 directly in line with the nozzle 14 to permit a ribbon of cement to pass downwardly out of the nozzle 14 and along the edge of the particular plate 7, which is at that time on top of the assembly 6. When the carriage 16 has moved to the opposite end of its travel, it opens the limit switch 20 to thereby deenergize the solenoid 21 to permit the tension spring to close the valve structure 23, stopping the flow of cement out of the nozzle :14.

A workman may then place another plate 7 upon the plate structure 6 accompanied by one or more spacers 15, and upon movement of the carriage 16 toward the left, the limit switch 20 will reclose to again energize the solenoid 21 to open the valve structure 23 to thereby permit a pair of ribbons of cement to flow along the opposite edges of the upper plate 7. Upon return of the carriage 16 to its extreme leftward position, as shown in Fig. 3, the limit switch 19 is again opened to deenergize the circuit through the solenoid 21, thereby permitting the tension spring 25 to close the valve structure 23, halting any further flow of cement out of the nozzles 13, 14. The cement may be placed under suitable pressure by any suitable means. In the particular form shown in Figure 3, a piston 27 is employed biased downwardly into compressive relation with the cement 28 'by means of a compression spring 29.

The carriage 16 maybe provided with side supports 30 and one ormore end supports 31. These side and end supports 30, 31 permit a workman to readily place additional plates 7 in the desired position without any means re quired for positional adjustment. Before each additional plate 7 is placed in position, the spacer strips 15 are disposed at the opposite ends of the plates 7 to maintain the required distance between the plates 7 prior to the hardening of-the cement '28 inthe baking operations.

Referring to Fig. 4, it will be noted that the ribbons of cement 32 when hardened form the insulating elongated spacer strips 9, previously referred to which are disposed between the plates 7 along the outer edges thereof.

Any suitable cement may be employed in our improved process. Preferably, the cement should have twoproperties. It should be resilient so as to accommodate irregularities in the plate 7 which may not be exactly fiat. Also,

the cement should be free from carbonization so that during operation of the interrupter the resulting high temperature caused by the arc will not carbonize and tend to decompose the-cement spacing between the plates 7. Preferably, the cement should have a major portion of finely divided inorganic insulating substance, such as powdered asbestos, powdered glass fibers, silica flour or mica 'fiour or crushed limestone, and a minor proportion of harden-able binder, such as urea-formaldehyde resin, melamine formaldehyde resin or sodium silicate.

Thus, we do not confine our invention to any particular cement. Any cement of the general composition as above mentioned may be suitable. However, a particular .cement, which we deem particularly satisfactory, is a cement made by mixing ground asbestos with a sticking and bonding agent, such as urea-formaldehyde varnish, the latter containing considerable calcium carbonate pigment for body. The asbestos and varnish are'mixed together in proportions that will give a heavy-bodied cement which will extmde easily, be sticky, and "have-sufiicient body to hold its shape well. Satisfactory results were obtained with a mixture of two parts of asbestos to one part varnish by weight. This cement may be placed in the gun 12 and extruded from the nozzles 13, 14 in the apparatus disclosed in Figs. 3 and 4. Preferably, the nozzles have a diameter somewhat larger than the plate spacing. The assembly fixture or carriage 16 is provided to bring about relative motion between the plates 7 and the nozzles 13, 14. The nozzles 13, 14 will then lay a pair of ribbons of cement on each edge of each plate 7. The insulating spacers 15 are placed at the ends and the next plate 7 placed upon the stack 6 so that two more ribbons of cement may be extruded on the new plate and the process repeated until the stack is built. When the stack 6 has set long enough for the cement to partially set up, it is transferred to a baking fixture and baked. After the assembly 6 has been baked, the insulating spacers 15 may be removed since the cement is sufficiently hard at this stage of the operation to provide the sole spacing means between the several plates 7.

A variation of the foregoing process may be carried out in the following manner, referring to Figs. 5-7. The plates 7 are clamped in an assembly fixture with stepped spacers 34 between the plates. When the assembly is first made, the thicker section of the spacers 34 separate the plates 7, as indicated in Fig. 6. Cement, as previously described, is rolled out on a sheet of paper 35, as shown in Fig. 5, to a thickness of about inch. This sheet 35 is transferred to the edge of the assembly and placed cement side down, and pressed or rolled, as with a suitable rolling pin 36, which forces the cement 28 between the edges of the plates 7.

The assembly 6 is then turned over and the process repeated on the opposite edges. The spacers 34 are now pulled out to where the thinner section 37 is between the plates 7, and the jig is clamped to bring the plates against the spacers again. This compacts the cement 28 and forms a better bond (see Fig. 7). The assembly 6--i s' then transferred to a baking fixture and baked as before. Following the baking operation, the stepped spacers 34 may be removed.

Instead of using paper as a backing for the cement to form it into a thin layer, a gun 38 may be used with ;a long nozzle 39. The extruded cement will be in sheet form, as shown in Fig. 8, and may be pressed by rollers, or the like, between the plates 7. Stepped spacers 34, as before, may be used.

These two methods of providing a spacing means between the plates 7, cut down the assembly time and eliminate the expense connected with the cementing and assembling of the spacer strips formerly used. The baked cement between the plates has been found to have good insulating characteristics, and a stack 6 of such plates 7 was tested on successive arc interruptions and found to be very satisfactory.

The foregoing description of our invention discloses methods of eliminating the spacer strips used before and providing a simple and inexpensive and fast method of.

assembling the plates 7 into an interrupting stack 6. Cost has been reduced and uniformity achieved. Furthermore, the time involved in assembling the plates has been greatly cut down, and the cement has been found to adhere well to the plates 7 andprovide a desirable spacing means separating successive plates 7 the desired distance apart.

Although we have shown and described severalmethods of assembling the plate structure 6, it is to be clearly understood that these were merely for the purpose of illustration, and that changes and modificationsmay readily be made therein by those skilled in the art without departing from the spirit and scope of the appendedclaims.

We claim as our invention:

1. The method of manufacturing spaced stacked plate are extinguishers having venting passages between the plates and provided by the adhesive betweemsaid plates comprising spreading cement upon aflat backingfholding a plurality of plates in spaced superimposed relationship by a plurality of stepped spacers with the larger width of the spacers between the plates, placing the layer of cement and backing along the side of the plate structure with the cement side against the plates, forcing the cement between the plates by exerting pressure against the backing, pulling the spacers out from between the plates while they are under compression until the smaller width of the spacers is between the plates, and then baking the plate structure until the cement hardens.

2. The method of forming spaced stacked plate are chutes having rectangularly-shaped venting passages between the plates provided by the adhesive between said plates comprising the steps of: assembling at one time a stack of superimposed flat rigid rectangularly-shaped plates spaced apart by temporary stepped spacers at the narrow edges thereof with the larger width of the spacers between the plates, applying cement along the edges of the assembled plates with the larger width of the temporary stepped spacers therebetween, partially removing the stepped spacers until the smaller width of the spacers is between the plates with pressure on the stack to slightly compact the cement, baking the cement until it hardens, and finally removing the stepped temporary spacers from between the plates after the cement has hardened.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,572 Curran et al. Nov. 11, 1952 1,595,810 Allcutt Aug. 10, 1926 1,825,308 Dorogi et a1 Sept. 29, 1931 1,947,139 Peters Feb. 13, 1934 2,154,333 Kampfer Apr. 11, 1939 2,249,499 Seaman July 15, 1941 2,264,628 Engert et a1 Dec. 2, 1941 2,428,979 May Oct. 14, 1947 2,442,199 Dickinson et al. May 25, 1948 2,548,468 Crise Apr. 10, 1951 2,556,011 Swayze et al. June 5, 1951 2,566,249 Rainey et al Aug. 28, 1951 2,581,845 Elliott Jan. 8, 1952 2,608,502 Merriman Aug. 26, 1952 2,616,482 Barnes Nov. 4, 1952 

1. THE METHOD OF MANUFACTURING SPACED STACKED PLATE ARC EXTINGUISHERS HAVING VENTING PASSAGES BETWEEN THE PLATES AND PROVIDED BY THE ADHESIVE BETWEEN SAID PLATES COMPRISING SPREADING CEMENT UPON A FLAT BACKING, HOLDING A PLURALITY OF PLATES IN SPACED SUPERIMPOSED RELATIONSHIP BY A PLURALITY OF STEPPED SPACERS WITH THE LARGER WIDTH OF THE SPACERS BETWEEN THE PLATES, PLACING THE LAYER OF CEMENT AND BACKING ALONG THE SIDE OF THE PLATE STRUC- 